Conversion of hydrocarbon oils



Sept. 29, 1936. J. B. HEID 2,055,896

' CONVERSION OF HYDROCARBON OILS Original Filed April 50, 1934FRACTIONATOR l RECEIVER 47 9 HEAT EXCHANGER FURNACE INVENTOR JACOB BE INHEID TORNEY Patented Sept. 29, 1936 CONVERSION OF HYDROCARBON OILS JacobBenjamin Held, Chicago, 111., assignor to Universal Oil ProductsCompany, Chicago, 111., a corporation of Delaware Application April 30,1934, Serial No. 723,125 Renewed August 1, 1935 11 Claims. (CL 196-48)This invention particularly refers to an improved process for theconversion of hydrocarbon oils of the type wherein selected relativelylow boiling and high boiling fractions of the intermediate conversionproducts of the process (reflux condensate) are each subjected toindependently controlled conversion conditions in the same system. Theimprovements of the present invention comprise methods for subjectingnormally gaseous products of the process, as well as, when desired,gases from any desired external source, to two-stage absorption, raw oilcharging stock for the process being utilized as the absorber oil in onestage and the enriched raw oil being subjected to conversion, togetherwith high boiling fractions of the intermediate conversion products ofthe process, while selected low boiling fractions of the intermediateconversion products are utilized as absorber oil in the other stage, theenriched oil from this stage being subjected to independently controlledmore severe conversion conditions in the same system.

The advantages of recovering desirable high boiling components, such aspropane, butane and their corresponding olefins, for example, from thegaseous products resulting from the pyrolytic conversion of hydrocarbonoils for the production of high yields of good quality motor fuel andsubjecting the same to conversion, together with the absorbing menstruumutilized for their recovery, have already been demonstrated. I am awarethat it has been the practice to utilize hydrocarbon oil charging stockof a relatively high-boiling nature as the absorber oiLin such processesand that selected low boiling fractions of the intermediate conversionproducts (reflux condensate) from within the system have also beensuccessfully utilized for this purpose.

It is generally recognized that an absorbing medium only slightly higherin boiling characteristics than the material to be absorbed isordinarily more eflicient than an absorbing medium of considerablyhigher boiling characteristics. For this reason a low-boiling fractionof the intermediate conversion products of the process is preferable forabsorbing propane, butane and the like from the gaseous conversionproducts to higher boiling charging stock for the process.

I have also found that by the inclusion of addi-- tional quantities ofthe desirable high boiling components of the gases such as propane,butane and the like to the oils undergoing conversion, in excess of thepropanes, butanes, etcetera, normally produced within the system,additional yields of motor fuel of improved quality may be produced.

This may be accomplished, for example, by supplying gases containing thedesired materials from any suitable external source to the absorptionstage of the process and, while I have not determined the exact limitswithin which improved results a-re obtainable from a commercialstandpoint by the addition of increased quantities of normally gaseousmaterial such as propane and butane to the oil undergoing conversion, Ibelieve that the quantities of such materials which may beadvantageously employed is relatively high and that it variesappreciably with different types of oil as well as with the conversionconditions to which they are subjected.

Furthermore, I have found that the same or an even greater increase inthe yield of desirable light liquid products, such as motor fuel of highanti-knock value, may be obtained by the conversion of propanes, butanesand similar materials with a select low boiling fraction of theintermediate conversion products as compared to their conversion withhydrocarbon oil charging stock when the latter is of higher boilingcharacteristics comprising such materials as gas oil, fuel oil and thelike. However, the volume of select low-boiling fractions of theintermediate conversion products in an operation of the character abovementioned is sometimes not suflicient to.

recover all of the available desired components of the gases,particularly when the gases produced within the system and subjected toabsorption are augmented by gases from an external source. Therefore, inthe present invention, in addition to subjecting the gases to adsorptionwith the relatively light intermediate conversion products, I employanother adsorption stage, utilizing hydrocarbon oil charging stock forthe process as the absorber oil, subjecting the enriched hydrocarbon oilcharging stock to conversion conditions of elevated temperature andsuperatmospheric pressure, together with high boiling fractions of theintermediate conversion products of the process and subjecting theenriched absorber oil from the other stage to independently controlledmore severe conversion conditions of elevated temperature andsuperatmospheric pressure in the same cracking system. By this method ofoperation I am not only able to recover substantially all of the highboiling components of the gases but, due to the relatively large volumeof total absorber oil available, I may, when desired, supply additionalgases from any suitable external source to the system for absorption,thereby materially increasing the total quantity of normally gaseousmaterial, such as propane and butane, subjected to conversion within thesystem together with the absorber liquid and increasing both the yieldand quality of the motor fuel conversion products of the process.

The features of the present invention may be utilized to advantage inpractically any type of cracking system wherein relatively low boilingand high boiling oils are subjected to independently controlledconversion conditions. It is within the scope of the invention to employa selected low boiling fraction of the intermediate conversion productsof the process as the absorber liquid in the first absorption stage,followed by subjection of the remaining gases to absorption withhydrocarbon oil charging stock for the process in the second absorptionstage or, when desired, this order may be reversed, the raw oil beingutilized as the absorption medium in the first stage and the selectedlow boiling fractions of the intermediate conversion products utilizedas the absorption medium in the second stage.

Further details of the preferred operation of the process as well asalternatives which are permissible within the scope of the inventionwill be more apparent with reference to the accompanying diagrammaticdrawing and the following description thereof. The drawing illustratesone specific form of apparatus in which the invention may be practiced.

Referring to the drawing, heating coil 4 is located within a furnace 2of any suitable form and the oil supplied to this zone, as will be latermore fully described, is subjected to the desired conversiontemperature, preferably at a substantial superatmospheric pressure, thestream of heated oil being discharged from the heating coil through line3 and valve 4 and introduced into reaction chamber 5.

Chamber 5 is also preferably maintained at substantial superatmosphericpressure and, although not indicated in the drawing, is preferably wellinsulated to prevent the excessive loss of heat by radiation so thatconversion of the heated products supplied to this zone, andparticularly their vaporous components, may continue therein. In theparticular case here illustrated, both vaporous and liquid conversionproducts are withdrawn in commingled state from the lower portion ofchamber 5, passing through line 6 and valve 1 into vaporizing chamber 8.

Chamber 8 is preferably maintained at substantially reduced pressurerelative to that employed in the reaction chamber, by means of whichfurther vaporization of the liquid conversion products supplied to thiszone is accomplished. Residual liquid remaining unvaporized in chamber 8may be withdrawn therefrom through line 9 and valve 10 to cooling andstorage or to any desired further treatment or, when desired, theconditions of operation may be regulated to affect the production ofsubstantially dry coke as the residual conversion product of theprocess. In the latter case the coke may be allowed to accumulate withinchamber 8, or a similar coking zone of any desired form (not shown), tobe removed therefrom after the operation of the chamber is completedand, when desired, a plurality of such zones may be employed and may beoperated either alternately or simultaneously. When coke is produced inchamber 8 as the final residual product of the process line 9 and valveIt! may serve as a drain line and as a means of introducing steam, wateror other suitable cooling medium into the chamher after its operation iscompleted, in order to hasten cooling and facilitate cleaning of thechamber. The vaporous conversion products of the process pass, in thecase illustrated, from chamber 8 through line H and valve l2 tofractionation in fractionator l3.

The components of the vaporous conversion products supplied tofractionator l3 boiling above the range of the desired final lightdistillate product of the process are condensed within this zone asreflux condensate and the reflux condensate is separated into selectedlow boiling and higher boiling fractions. The high boiling fractions ofthe reflux condensate may collect within the lower portion offractionator I3 to be withdrawn therefrom through line [4 and valve l5to pump I3, by means of which they are returned through line I! andvalve I8 to further conversion in heating coil I. The selected lowboiling fractions of the reflux condensate may be withdrawn from anysuitable intermediate point or plurality of points in column l3, forexample through line I9 and valve 20, to pump 2| by means of which theyare fed through line 22 and may be directed through valves 23 and 24 inthis line to absorber 55 or they may be subjected to cooling, whendesired, prior to their introduction into the absorber in any suitablemanner, for example, by passage through heat exchanger 25 and/or cooler26.

Heat exchanger 25 serves as a means of obtaining indirect contact andheat exchange between low boiling fractions of the reflux condensatefrom fractionator l3 and enriched hydrocarbon oil charging stock for theprocess, which latter is supplied to this zone, as will be later morefully described. Lines 21 and 29, controlled by the respective valves 28and 3D, serve, in conjunction valve 23 in line 22, to regulate the flowof low boiling reflux condensate through heat exchanger 25.

Cooler 25 which, in the case here illustrated, is of the immersed,open-coil type around which water or any other suitable cooling mediummay be circulated by any suitable well known means (not shown). Thiszone serves as a means of further cooling the absorber oil supplied tocolumn 55 to the desired degree and its flow through this zone isregulated by valves 32 and 36 in the respective lines 3! and 33 inconjunction with valve 24 in line 22.

Fractionated vapors of the desired end-boiling point are withdrawn,together with gaseous products produced by the process, from the upperportion of fractionator [3 through line 35 and valve 36 to be subjectedto condensation and cooling in condenser 31. The resulting distillateand gas may pass through line 38 and valve 39 to collection andseparation in receiver 40.

Distillate may be withdrawn from the receiver through line GI and valve42 to storage or to any desired further treatment and, when desired, aregulated portion of the distillate collected in receiver may bewithdrawn therefrom through line 33 and valve 44 to pump 45 by means ofwhich it is recirculated through line 46 and valve l! to the upperportion of fractionator 13 to serve as a cooling and refluxing medium toassist fractionation of the vapors and to maintain the desired vaporoutlet temperature from the fractionator.

The gaseous products of the process are withdrawn from receiver 40through line 48 and valve 49 to pump or compressor 50 by means of whichthey are supplied through line 5| and valve 52 to absorber 55. Whendesired, gases of suitable composition, preferably containing desirablehigh boiling components such as propane, butane and the like from anexternal source may be supplied by means of line 53 and valve 54 toabsorber 55, together with the gases produced within the system. Suchexternal gases, when employed, may comprise, for example, gasesrecovered by the stabilization of distillate from receiver 40, gasesfrom a separate cracking process or from any other suitable gas makingprocess or natural gas. Preferably, however, the material selected forthis purpose contains a considerable proportion of the desired highboiling components of the gaseous conversion products of the processsuch as propane, butane and/or the corresponding oleflns.

Absorption columns 55 and 55 are similar zones containing any suitablemeans (not shown), such as bubble trays, perforated pans, packing or thelike or any desired combination of such means, whereby intimate contactis obtained between the gases and the absorber liquids. The gases notabsorbed by contact with the selected low boiling fractions of thereflux condensate in column 55 pass from the upper portion of this zonethrough line 51 and valve 58 to be subjected to further absorption withraw oil charging stock for the process in column 56. The gases remainingafter absorption in column 56 may be withdrawn from the upper portion ofthis zone and from the system through line BI and valve 82 to storage orelsewhere, as desired. The selected low-boiling fractions of the refluxcondensate supplied as described to column 55and enriched therein byabsorption of liquefiable components of the gases.

are withdrawn from the lower portion of column 55 through line 59 andvalve 60 to pump 6! by means of which they are fed through line 62 andvalve 63 to further conversion in heating coil 64.

Heating coil 64 is located within a furnace 65 of any suitable form bymeans of which the required heat is supplied to the oil passing throughthe heating coil to bring it to the desired conversion temperaturepreferably at a substantial superatmospheric pressure. The stream ofhighly heated oil is discharged from heating coil 64 through line 66 andmay be directed through valve 61 in this line and line 3 into reactionchamber 5, together with heated products from heating coil I, or may beseparately supplied to the reaction chamber at any desired point in thiszone, by well known means (not shown). It is also within the scope ofthe invention, although not illustrated in the drawing, to supply aregulated portion or all of the hot conversion products from heatingcoil 64 to chamber 8 to serve as a means of assisting vaporization inthis zone, particularly in case the process is operated for the production of coke as the residual conversion product of the process inchamber 8.

Hydrocarbon oil charging stock for the process may be supplied throughline 68 and valve 69 to pump 10 by means of which it is supplied, in theparticular case here illustrated, through line H and valve 12 to column56 to serve as an absorbing medium for the gases from column 55. Theenriched hydrocarbon oil charging stock from column 56 may be withdrawnfrom the lower portion of this zone through line 13 and valve 14 to pump15 by means of which it is fed, in the case here illustrated, throughline 16, valve 11, heat exchanger 25, line 18, valve 19 and line l'l toconversion in heating coil i, together with high boiling fractions ofthe reflux condensate from fractionator II. It will be understood that,when desired, all or a regulated portion of the enriched charging stockmay by-pass heat exchanger 25, by well known means (not shown) and also,when desired, only a regulated portion of the charging stock may beutilized as absorber oil in column 55, the remainder being suppliedeither to heating coil I or to fractionator i3, by well known means (notshown).

It is also within the scope of the invention, when desired, instead ofsupplying'selected low boiling fractions of the reflux condensate tocolumn 55 and hydrocarbon oil charging stock to column 56 to reversethis arrangement by well known means (not shown) supplying hydrocarbonoil charging stock to the first absorption stage and selected lowboiling fractions of the reflux condensate to the second absorptionstage of the process.

It will be understood that the various alternative methods of operationmentioned are not to be considered equivalent but may be selected tosuit requirements, the mode of operation being varied, for example, withdifferent types of charging stock as well aswith variations in thecracking conditions employed within the system and the desired results.

In a process such as illustrated and above described the preferred rangeof operating conditions may be approximately as follows: The heatingcoil to which the enriched charging stock and high boiling fractions ofthe reflux condensate are supplied may utilize a conversion temperature,measured at the outlet from this zone, ranging, for example, from 850 to950 F., or thereabouts, preferably with a superatmospheric pressure atthispoint in the system of from 100 to 500 pounds, or more, per squareinch. The heating coil to which the selected enriched low boilingfractions of the reflux condensate are supplied preferably employs ahigher conversion temperature than that utilized in the other heatingcoil ranging, for example, from 900 to 1050 F., or more, preferably witha superatmospheric pressure, measured at the outlet from the heatingcoil, of from 200 to 800 pounds, or more, per square inch. A pressuresubstantially equalized or somewhat reduced relative to that employed inthe heating coil utilizing the lowest pressure, in case differentpressure conditions are employed in the two heating coils, may beutilized in the reaction chamber, this pressure ranging, for example,from 100 to 500 pounds, or more, per square inch. The pressure employedin the vaporizing chamber, as already mentioned, preferably issubstantially reduced relative to that employed in the reaction chamberand may range, for example, from 100 pounds, or thereabouts, per squareinch, down to substantially atmospheric pressure. The pressures employedinthe fractionating, condensing and collecting portions of the crackingsystem may be either substantially equalized or somewhat reducedrelative to the pressure employed in the vaporizing chamber. The twoabsorption stages of the system may utilize substantially the same ordifferent pressures ranging, for example, from substantially atmosphericto 300 pounds, of thereabouts, per square inch. The relatively lowboiling fractions of the reflux condensate selected as an adsorber oilmay be within the boiling range of 350 to 650 F., for example, althougha somewhat narrower boiling fraction within substantially this range isordinarily preferred.

As a specific example of one of the many possible operations of theprocess of the present invention, as it may be practiced in an apparatussuch as illustrated and above described, the charging stock is aMid-Continent topped crude of about 30 A. P. I. gravity which, afterbeing utilized as absorber oil in the second absorption stage of theprocess, is subjected while still in admixed form with components suchas propane and butane absorbed from the gases to a conversiontemperature of approximately 930 F., at a superatmospheric pressure ofabout 300 pounds per square inch. This pressure is substantiallyequalized in the reaction chamber and a pressure of approximately 30pounds per square inch is employed in the succeeding vaporizing chamberwherein the residual conversion products of the process are reduced tocoke. A pressure substantially equalized with that employed in thecoking zone is utilized in the succeeding fractionating, condensing andcollecting portions of the cracking system and high boiling fractions ofthe reflux condensate are returned to further conversion, together withthe enriched charging stock. Selected low boiling fractions of thereflux condensate, boiling within the range of substantially 400 to 550F., are utilized as absorber oil in the first absorption stage of thesystem. The gases subjected to absorption comprise uncondensable gasesrecovered from the receiver of the cracking system as well as gasesrecovered by stabilization of the light distillate product of theprocess and an approximately equal amount of similar gases from anothercracking system. The enriched selected low boiling fractions of thereflux condensate are subjected in a separate heating coil to an outletconversion temperature of approximately 995 F. at a superatmosphericpressure of approximately 800 pounds per square inch. A regulatedportion of the heated products from this zone is introduced into directcontact with the residual products of the process undergoing coking forthe purpose of assisting their reduction to coke and the remainder aresupplied to the reaction chamber. This operation will produce, perbarrel of charging stock, approximately 65% of motor fuel having ananti-knock value equivalent to an octane number of approximately 70 andabout 70 pounds of coke of relatively low volatility, the remainderbeing chargeable principally to lean uncondensable gas.

I claim as my invention:

1. In a process for the conversion of hydrocarbon oils wherein the oilis subjected to conversion conditions of elevated temperature andsuperatmospheric pressure, the resulting vaporous and residualconversion products separated, the vapors subjected to fractionationwhereby their insufliciently converted components are condensed asreflux condensate, fractionated vapors of the desired end boiling pointsubjected to condensation and the resulting distillate and gas collectedand separated, the improvement which comprises separating the refluxcondensate into selected low boiling and high boiling fractions,subjecting the latter to said conversion, subjecting the gas toabsorption by intimate contact with selected low boiling fractions ofthe reflux condensate to recover desirable high boiling components ofthe gases such as propane and butane, subjecting the remaining gases tofurther absorption by intimate contact with hydrocarbon oil chargingstock for the process whereby to recover additional quantities ofdesirable high boiling components of the gases, subjecting the chargingstock enriched by said absorption to conversion, together with said highboiling fractions of the reflux condensate, subjecting the selected lowboiling fractions of the reflux condensate enriched by said absorptionto independently controlled conversion conditions of elevatedtemperature and superatmospheric pressure and commingling the vaporousproducts from both conversion stages, prior to their fractionation.

2. In a process for the conversion of hydrocarbon oils wherein the oilis subjected to conversion conditions of elevated temperature andsuperatmospheric pressure, the resulting vaporous and residualconversion products separated, the vapors subjected to fractionationwhereby their insuflficiently converted components are condensed asreflux condensate, fractionated vapors of the desired end boiling pointsubjected to condensation and the resulting distillate and gas collectedand separated, the improvement which comprises separating the refluxcondensate into selected low boiling and high boiling fractions,subjecting the latter to said conversion, subjecting the gas toabsorption by intimate contact with hydrocarbon oil charging stock forthe process to recover desirable high boiling components of the gasessuch as propane and butane, subjecting the remaining gases to furtherabsorption by intimate contact with selected low boiling fractions ofthe reflux condensate whereby to recover additional quantities ofdesirable high boiling components of the gases, subjecting the chargingstock enriched by said absorption to conversion, together with said highboiling fractions of the reflux condensate, subjecting the selected lowboiling fractions of the reflux condensate enriched by said absorptionto independently controlled conversion conditions of elevatedtemperature and superatmospheric pressure and commingling the vaporousproducts from both conversion stages, prior to their fractionation.

3. In a process for the conversion of hydrocarbon oils wherein the oilis subjected to conversion conditions of elevated temperature andsuperatmospheric pressure, the resulting vaporous and residualconversion products separated, the vapors subjected to fractionationwhereby their insufliciently converted components are condensed asreflux condensate, fractionated vapors of the desired end-boiling pointsubjected to condensation and the resulting distillate and gas collectedand separated, the improvement which comprises separating the refluxcondensate into selected low boiling and high boiling fractions,subjecting the gases to absorption for the recovery of their desirablehigh boiling components such as propane and butane in two separateabsorbers connected in series, utilizing hydrocarbon oil charging stockfor the process as absorber oil in one absorber, utilizing selected lowboiling fractions of the reflux condensate as absorber oil in the otherabsorber, subjecting hydrocarbon oil charging stock enriched by saidabsorption to said conversion, together with the high boiling fractionsof the reflux condensate, subjecting the selected low boiling fractionsof the reflux condensate enriched by said absorption to independentlycontrolled conversion conditions of elevated temperature andsuperatmospheric pressure and commingling the vaporous products fromboth conversion stages of the system, prior to their fractionation.

4. A process of the character defined in claim 3, wherein the selectedlow boiling fractions of the reflux condensate utilized as absorber oilare cooled to the desired degree, prior to their contact with saidgases.

5. A process of the character defined in claim 3, wherein the selectedlow boiling fractions of the reflux condensate utilized as absorber oilare cooled to the desired degree, prior to their contact with saidgases, said cooling being eflected, at least in part, by indirectcontact and heat exchange with said enriched hydrocarbon oil chargingstock.

6, A process of the character defined in claim 3, wherein hydrocarbongases from an external source, containing desirable high boilingcomponents such as propane and butane, are commingled in regulatedamounts with the gaseous products of the process subjected to saidabsorption.

'7. A hydrocarbon oil conversion process which comprises fractionatingcraokedvapors, formed as hereinafter set forth, to separate heavierfractions thereof as reflux condensate, subjecting hydrocarbon gases,contaiing high boiling components such as propane and butane, toabsorption in separate absorption stages, scrubbing the gases in one ofsaid stages with charging oil to be cracked, scrubbing the gases inanother of said stages with at least a portion of said refluxcondensate, subjecting the enriched charging oil and the enriched refluxcondensate to independently controlled cracking conditions oftemperature and pressure in separate conversion zones, and supplying theresultant vaporous conversion products to the fractionating step as saidcracked vapors.

8. A hydrocarbon oil conversion process which comprises fractionatingcracked vapors, formed as hereinafter set forth, to separate heavierfractions thereof as reflux condensate, finally condensing thefractionated vapors and separating the condensed portion thereof fromincondensable gases, subjecting the latter to absorption in separateabsorption stages, scrubbing the gases in one of said stages withcharging oil to be cracked, scrubbing the gases in another of saidstages with at least a portion of said reflux condensate, subjecting theenriched charging oil and the enriched reflux condensate toindependently controlled cracking conditions of temperature and pressurein separate conversion zones, and supplying the resultant vaporousconversion products to the fractionating step as said cracked vapors.

9. A conversion process which comprises heating hydrocarbon oil tocracking temperature of said reflux condensate and then with chargingoil. for the process, supplying the enriched charging oil to said coil,subjecting the enriched reflux condensate in a second heating coil toindependently controlled cracking conditions of temperature andpressure, and supplying vaporous products of this independent conversionto the fractionating step.

10. A conversion process which comprises heating hydrocarbon'oil tocracking temperature under pressure in a heating coil, fractionating theresultant vapors to separate reatively heavy and light refluxcondensates therefrom, returning the heavy reflux condensate to theheating coil, finally condensing the fractionated vapors and separatingthe resultant final condensate from incondensable gases, scrubbing thegases first with the light reflux condensate and then Withcharging oilfor the process, supplying the enriched charging oil to said coil,heating the enriched light reflux condensate in a second heating coil tohigher cracking temperatures than the heavy reflux condensate andenriched charging oil in the first-named coil, and supplying vaporousconversion products of the enriched light reflux condensate to theaforesaid fractionating step.

11. In a hydrocarbon oil conversion process wherein charging oil for theprocess and reflux condensate are subjected to independently controlledcracking treatments, the improvement which comprisesscrubbingincondensable gases produced in the process with the chargingoil and with the reflux condensate in separate stages, and supplyinghigh boiling components thus separated from the gases to said crackingtreatments in admixture with the charging oil and reflux condensate. v

. JACOB BENJAMIN HEID.

